


In Another World

by NerdofSpades



Series: Open Doors [16]
Category: Assassination Classroom, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: AU of an AU, Gen, Midoriya Izuku HAS One For All, Paperwork, Quirk Training, not compliant with the rest of the series
Language: English
Status: Completed
Published: 2019-12-19
Updated: 2019-12-19
Packaged: 2021-02-25 23:21:21
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,923
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21863653
Author URL: https://archiveofourown.org/users/NerdofSpades/pseuds/NerdofSpades
Summary: Midoriya Izuku has One for All. He never changed his mind about wanting it. Now, entrance exams are over and he has a quirk he doesn't know how to use. Luckily, he knows some people who are more than willing to help him figure it out.orIzuku chose to keep going as All Might's successor, and Karasuma Tadaomi knows a lot about quirks. (THIS IS NOT COMPLIANT WITH THE REST OF THE SERIES.)
Relationships: Karasuma Tadaomi & Midoriya Izuku, Korosensei (Assassination Classroom) & Midoriya Izuku, Midoriya Inko & Midoriya Izuku
Series: Open Doors [16]
Series URL: https://archiveofourown.org/series/1350022
Comments: 27
Kudos: 305





	In Another World

**Author's Note:**

> THIS IS NOT COMPLIANT WITH THE REST OF THE SERIES! In the very beginning, before I started writing or really getting into it, I thought I was going to have Izuku still get OfA from All Might. This scene comes from that line of thought. I had it all planned out and I loved it, then I realized Izuku would have changed his mind about the quirk and the entire scene was unusable. I didn't want to lose it, so now you all get to see it.

Izuku chewed on his lip as he looked at his phone for the hundredth time that night. The test was over. He failed and now Yagi-san wasn’t responding, but he needed to talk to him. He didn’t… he wasn’t going to focus on the test right now. That part was done. His new quirk was a different problem. He needed to get it under control. He needed to get it registered, but he had no idea how to do that.

And Yagi-san wasn’t responding. Probably because Izuku was such a failure. He’d probably ask for his quirk back when he got around to talking to Izuku and…

No. That wasn’t going to happen. That wasn’t how this was going to work. Even if Izuku failed to get into UA’s heroics course, he was pretty sure he’d gotten into Toku and General Studies. He still had a chance. Sure, he wouldn’t necessarily be with All Might, but he could make this work.

It wasn’t like UA was his only option, just like Yagi-san wasn’t the only person that could help Izuku right now. Karasuma-sensei had been a major help to Izuku’s classmates, not just in getting them physically trained to be assassins, but also in helping them learn to control and use their quirk to get the most out of it.

Not to mention he was a government agent that probably knew how to get a formerly quirkless kid registered as having a quirk.

Izuku picked up his cell phone, hesitated one last second before squashing down his doubts, and dialing the number.

The phone rang once. Twice. Three times. Four. _“Hello? Midoriya-kun, are you alright?”_

Izuku’s face burned. “U-uh, y-yeah. I’m fine, Karasuma-sensei.”

_"Then what can I help you with? I doubt you called this late in the day for nothing.”_

“Right, of course not. I… I developed a…” Great. He had no idea how to explain this. He had been quirkless for fifteen years for crying out loud! How was he supposed to explain how he got a quirk?

_“Midoriya-kun? Are you still there?”_

“Y-yeah… I guess I don’t really know how to explain this.”

_"Do you need me to come to you? Or want me to?”_

“N-no. That won’t be necessary.”

_“Then I suggest by just saying whatever you need to say. Worry about explaining any details later. Just… get it out.”_

No way it could be that easy. “Alright then.” Izuku took a deep breath. “I have a quirk now.”

There was silence on the other end. _“You’re a late bloomer?”_

Wait, what? “What…?”

_“Don’t worry about it too much, Midoriya-kun. It’s not common, but people have quirks they don’t figure out pretty often. Sometimes because it has a super specific trigger or use that they don’t come across in their lives, sometimes just because. It’s not a huge deal.”_

Izuku could hardly believe it. “Um, yeah. I guess I am. I was, uh, hoping you could help me get it under control and figure it out and all that.”

_“Is it causing any problems for you right now?”_

“Uh, no. I have on and off down, but anything more than that is beyond me. I won’t use it by accident.”

_“Good. Do you have any plans for tomorrow after school?”_

Izuku shook his head. “Just lessons with Sentoki-sensei later in the evening.”

_“Then I’ll bring the paperwork to get your quirk registered, and we can fill it out and work on your control after classes let out. Tell your mom and bring some extra food for dinner. I’ll let you go when you need to leave for Sentoki-san.”_

Izuku’s shoulders fell and a weak smile pulled at his lips. “Thank you, Sensei.”

_“Don’t worry about it. I don’t want you out in the world with a quirk you can’t control. If we have to work until your next school year starts, we will. I’ll help you as much as you need.”_

“Then, uh, I guess I’ll see you at school then?”

_“Of course. I’ll see you then.”_

The call ended. Izuku sighed and collapsed on his bed, a giddy laugh bubbling up from his chest. That was one problem handled.

* * *

Izuku sat across from Karasuma-sensei out on the sports field. They would be using the office, but Karasuma-sensei wanted to get some distance from Korosensei while the nosy octopus was working on the yearbooks. “Let’s start with you describing your quirk,” Karasuma-sensei prompted.

Izuku nodded. “Well, it’s a pretty normal strength enhancing quirk,” he said. “When I activate it, some glowing red lines start crisscrossing the body part I’m enhancing… and it breaks my bones when I actually hit something.”

Karasuma-sensei stopped writing. “It breaks your bones?”

Izuku nodded.

“You said you have off and on figured out?”

Another nod.

“And how much force do you get from your quirk?”

Izuku’s face burned. “A lot. Like. _A lot._ ”

“Can you give me an example?”

“… How much do you know about UA’s entrance exam?”

“I know that the only reason they get away with it is because they have Recovery Girl on staff.”

“Do you know about the zero pointer?”

“… What did you do?”

“I knocked it out with one punch and broke all the bones in one arm and both legs in the process.”

Karasuma-sensei was staring at him. “Did you _know_ that was going to happen?”

Izuku shook his head. “It was the first time I ever used it. I kinda just… did.”

“I’m assuming you haven’t used it since?”

Izuku nodded quickly. “I don’t know how to use less power, so it would be foolish for me to go and destroy everything just to test it out.”

Karasuma-sensei sighed in relief. “At least you’re a smart one. Alright, do you have a name for it?”

“Uh… superpower?”

“Did you just make that up on the spot?”

“Maybe?”

“Well, too late to change it now. Is that everything you know about your quirk?”

“I guess so…”

Karasuma-sensei set the paperwork to the side. “What does it feel like when you use your quirk?”

Izuku paused. What had it felt like? With everything that had been going on… “Like… a rush? And a lot of pressure. Um… kinda like and egg in a microwave?”

“An egg in a microwave? Okay then. You said the red lines show up on the parts of your body it’s enhancing?”

Izuku nodded.

Karasuma-sensei thought for a moment. “You didn’t mention any kind of specific trigger, so I’m guessing you don’t need one?”

Izuku shook his head. “Uh… at least as far as I know!” he quickly tacked on.

Karasuma-sensei nodded. “Alright, I’ve got an idea. Have you ever tried meditation?”

Izuku’s nose scrunched up. “Once. I wound up mumbling a lot and never really got into that calm state your supposed to.”

“Okay, I want you to do something like that, but with your quirk. Don’t direct it or control it. Just turn it on and let it do what it wants.”

“Uh… the last time I used it, it kinda destroyed my clothes.”

Karasuma-sensei paused. “How much, exactly, was destroyed?”

“Just my sleeve, but it was completely gone.”

Karasuma-sensei nodded. “Go change into your old gym clothes then. We’ll get you settled when you get back.”

Izuku nodded and dashed off to change. When he returned, Karasuma-sensei was still there, but seemed to be writing something down. “I’m back, Sensei.”

Karasuma-sensei looked up. “Alright, take a seat. Do whatever you need to do to get comfortable.”

Izuku nodded and on the ground, hands resting on his knees with his legs tucked under him. “What now?”

“Close your eyes and activate your quirk,” Karasuma-sensei said. “Don’t give it a task. Don’t have a goal in mind. Just activate it. I’ll take a video so you can see it later. For now, I want you to focus on how it feels.” He pulled out his phone and started a recording.

“Um… alright. Here it goes,” Izuku muttered, closing his eyes. He leveled his breathing and turned his attention inward. He focused on that odd new part of him that he had discovered when One for All had activated for the first time, and poked at it, rousing the quirk. He pulled at it, tugging gently until he felt it expanding outward and moving to fill space, looking for something to do.

It moved quickly and suddenly, filling all the space it could occupy and then trying to push further, pressing out and in and on everything it could, yanking against whatever chained it to Izuku’s body.

It pressed, but it wasn’t as much as it had when he used it before. It wasn’t as overwhelming. It hurt, but… it was less explosive, less shattering. There was less pain.

Was his hair moving? Izuku felt like his hair was moving, but he couldn’t feel anything moving it? Hair wasn’t supposed to do that.

“Midoriya-kun? Are you doing alright?”

Izuku pulled in another breath. Was he doing alright? “Y-yeah. I think so. This is… different than it was before.”

“Alright, I want you to open your eyes now. Slowly.”

Izuku allowed his eyes to slide open, blinking slightly to readjust to seeing again. Was everything a little brighter now? That made some sense, seeing as his body started glowing last time. But… was it greener, too? Izuku couldn’t-

What was that? Was that a green… what? Lightning? Something electric. It felt electric and it was-

The pressure suddenly vanished, collapsing back in on itself and leaving a bone deep ache behind. Izuku fell backwards, groaning. It hurt, but more like a good exercise hurt. And he was tired. Exhausted even. He wasn’t sure how using his quirk like that had drained his energy, but it had.

“What happened?” Karasuma-sensei said, quickly stepping over to help Izuku up.

“I don’t know,” Izuku answered, biting back more groans as he moved. “I just… lost it.”

“And how do you feel now?”

“Tired and in pain. Kinda like I ran a kilometer then got hit by a bus.”

“We’re going to need to be careful in the future,” Karasuma-sensei said quickly. “Does anything feel broken?”

“I mean, it’s progress?” Izuku answered with a nervous laugh. “It’s better than the ‘arm smashed by passing bullet train’ I had before. And no, I don’t think anything’s broken.”

Karasuma-sensei hummed. “Can you stand for me?”

Izuku nodded and started pulling himself up, using Karasuma-sensei as an anchor. A hiss fell from his mouth as the pain suddenly spiked and his body protested loudly. He didn’t fall though. His legs held.

“Still don’t think it’s broken,” Izuku muttered as he tried to forcefully steady his breathing.

Karasuma-sensei didn’t answer, instead simply picking Izuku up bridal style and carrying him back to the schoolhouse.

Izuku glanced up at him “Thought you wanted to avoid Korosensei?” he said.

“I did, but there’s no way you’re going to become proficient with your quirk in the week we have left. You won’t be able to use it in an assassination. Not to mention you need to be looked over. So, yeah, we’re going inside and talking to him.”

Seeing as Karasuma-sensei had his hands full, he opted to avoid the doors and simply started yelling outside the office window. “Hey, open up! I need some help here!”

The window opened, and Korosensei stuck his grinning head out. “And what can I help you with, Karasuma-sensei?”

Karasuma-sensei held Izuku up a little higher and glared at Korosensei.

“Alright, alright.” Korosensei gently wrapped his tentacles around Izuku and lifted him from Karasuma-sensei’s arms. “I assume you’ll be in shortly.”

“I just need to grab some things before I forget them outside, then I’ll be in,” Karasuma-sensei said as he turned around and marched back to where he and Izuku had been working.

“Now then,” Korosensei said as he pulled Izuku in and set him in a chair, “what seems to be the problem?” He pressed a stethoscope to Izuku’s chest.

Izuku wasn’t even going to bother with the “when did he change into a doctor costume?” question because the answer was, “the second he wasn’t holding Izuku anymore.” “Just about everything hurts,” he answered instead.

“Everything?”

“Well, mostly my arms and legs, but yeah, everything hurts.”

“Hmmm, let’s see what the problem is.” Korosensei carefully rolled up one of Izuku’s pant legs and paused as he observed the limb. He began carefully poking and prodding the leg, and Izuku felt his body stiffen as he forced breath in between clenched teeth and he tried to resist the pain.

“Karasuma-sensei,” Korosensei began, voice flat and cold. “Mind explaining why Midoriya-kun had hairline fractures throughout his body?”

When had Karasuma-sensei entered the room? “There’s no way you diagnosed that without any equipment.”

“Don’t underestimate me.”

Karasuma-sensei shrugged his shoulders. “Midoriya-kun developed a quirk recently. I was trying to help him figure it out.”

“Oh?”

“Strength quirk,” Izuku said as the pain began to fade now that Korosensei wasn’t prodding at him. “First time it broke my bones.”

“So, this is an improvement,” Korosensei said, his usual joy returning to his voice. “Please, do be careful in the future, Midoriya-kun. And work hard to get a better handle on it.”

“Yes, Sensei.”

“Now, we should get you either home or to a doctor.”

“I’ll handle it,” Karasuma-sensei was quick to answer. “You just stay here and keep working on the yearbooks.”

“Alright, if you insist, Karasuma-sensei,” Korosensei chuckled. “I hope you’re looking forward to the finished books, Midoriya-kun. Oh, you’re all going to love them!”

Izuku gave him a strained grin. “Of course, we will. You don’t do anything halfway, Sensei.”

A sigh came from Karasuma-sensei. “Come on, kid. Let’s get you home,” he said as he picked Izuku up again.

The trek down the mountain was more treacherous than usual, given Karasuma-sensei was carrying Izuku the whole way down and didn’t have use of his hands. The car ride was silent, and getting Izuku’s mother to open the door was similar to how they got Korosensei to help, if more polite. (Karasuma-sensei kicked the door until someone answered.)

“What can I- Izuku!” Inko yelped as she recognized her son in Karasuma-sensei’s arms.

“Can I please come in, Midoriya-san?” Karasuma-sensei asked.

Inko mutely stepped aside and followed close behind the man as he strode through the apartment and deposited Izuku on the couch. Inko hovered for a second more, then rounded on Karasuma-sensei. “What happened!? Izuku told me he was staying late, but there’s no reason for him to need to be _carried home_!?”

“We were working with his quirk-”

“Izuku doesn’t have a quirk!”

Karasuma-sensei immediately turned his attention to Izuku. “Midoriya-kun, why does your mother not know you developed a quirk?”

“Uh…” Izuku muttered, eyes darting between two very angry adults.

“How about, while I explain things to Midoriya-san, you stay here and watch that video I recorded earlier. Then, when we get back, you can tell her why you hadn’t told her.”

“Yes, Sensei,” Izuku said.

Karasuma-sensei pulled out his phone and quickly handed it over after navigating to the video. With a small gesture, he guided Inko away from Izuku.

Izuku pressed play on the video. He ignored everything that was said. He remembered that. No, the interesting part was everything else. As he started, he saw the same glowing red lines covering his body that he had seen earlier. They were easily seen on every visible bit of skin and even glowed a little through the gym clothes. As quickly as they came, they faded back into his skin as some kind of phantom wind tugged at his hair and clothes and green flashes of… he was going to call it lightning began arcing over him. When Video-Izuku opened his eyes, Now-Izuku could see a faint glow to them.

It was amazing. Izuku had guessed from how he felt during and after that One for All had been acting on his body as a whole rather than focusing on a single limb the way he had used it earlier. He could also tell that he was still utilizing the full power of One for All, but that this was the correct way to do it. Even if he was still hurt pretty bad from just activating it, it probably would have been much worse if he’d actually done something with it. He’d probably still break his bones badly, even with the force dispersed better.

Now he just needed to figure out how to turn down the power. And what a safe level was.

Izuku played the video again. It really was amazing to watch.

Karasuma-sensei and Inko came back in. Inko looked calmer now that she had talked to Karasuma-sensei.

“Did you learn anything?” Karasuma-sensei asked as he took back his phone.

Izuku nodded. “Spreading it out seems to be the right way to utilize my quirk, but I still need to figure out how to lower the power level, so I don’t hurt myself.”

Karasuma-sensei nodded. To Inko he said, “I’ll leave the quirk registration papers here so you can get them filed. Other than that, Midoriya-kun should probably see a doctor soon, and definitely needs to rest.”

“Okay,” Inko replied. “Thank you for bringing him home.”

Karasuma-sensei bowed before turning to the door. “I’ll also call Sentoki-san, so she knows not to expect you for a little while. Take it easy, Midoriya-kun.” The door closed behind him.

“We have a lot to talk about, young man!”

Oh, this was going to be a long night.

**Author's Note:**

> So, yeah. This is right before the government fires Heaven's Lance. This version of Izuku would be in a world of pain while he tries to keep up with his classmates. Among other things.
> 
> Also, a quick head's up to everyone that actually bothers to read this, I am going to be travelling in the near future, so I'm not going to be able to post anything here until the end of January. In the meantime, a happy holidays to all of you, and I hope you have a great time.


End file.
